Long distance, top secret messages

Oct 19, 2010

When the military needs to send the key to encrypted data across the world, it can't necessarily rely on today's communication lines, where the message could be covertly intercepted. But physicists at the Georgia Institute of Technology in Atlanta are developing a new, more secure way to send such information across far distances, using existing cables and the laws of quantum mechanics.

Alex Kuzmich and colleagues have built a critical component of a quantum repeater, a device that allows -- such as the encryption keys used to encode data transmitted over traditional lines -- to be relayed over larger distances. They will describe this device at the Optical Society's (OSA) 94th annual meeting, Frontiers in Optics (FiO) 2010, at the Rochester Riverside Convention Center in Rochester, N.Y., from Oct. 24-28.

is an emerging technology currently used by both military and financial organizations to send information as entangled particles of light. In theory, anyone who tries to tap into this information changes it in a way that reveals their presence.

A quantum repeater is similar to a transformer on a traditional power line. Instead of converting electricity, it regenerates a communication signal to prevent it from degrading over distance. It contains two banks of memory, one to receive an entangled message and a second line to copy it.

Previously, the longest distance over which an encrypted key could be sent was approximately 100 kilometers. The new technology developed by the Georgia Tech team increases 30-fold the amount of time the memory can hold information, which means that series of these devices -- arrayed like Christmas lights on a string -- could reach distances in excess of 1,000 kilometers.

"This is another significant step toward improving systems based on . For quantum repeaters, most of the basic steps have now been made, but achieving the final benchmarks required for an operating system will require intensive optical engineering efforts," says Kuzmich.

Their device also converts the photons used in quantum devices from an infrared wavelength of 795 nm to a wavelength of 1,367 nm. This wavelength is used in traditional telecommunications lines, so the new device could someday plug into existing fiber optic cables.

"In order to preserve the quantum entanglement, we perform conversion at very high efficiency and with low noise," says Alexander Radnaev, who also works on this project at Georgia Tech.

Explore further: Endless oscillations: A theoretical study on quantum systems

More information: The talk, "Quantum Correlations Between Telecom Light and Memory" is at 9:15 a.m. on Wednesday, Oct. 27.

Related Stories

World Cup Security Uses Physics To Thwart Hackers

Jun 21, 2010

South African physicists working to protect data networks at the World Cup hope to provide something that no goalkeeper can promise: perfect defense. They're tapping the laws of physics to prevent hackers ...

Quantum electronics: Two photons and chips

Jan 20, 2006

Scientists at Toshiba Research Europe Limited (Cambridge, UK) believe they are on to a way of producing entangled twins of photons using a simple semiconductor electronic device. Such a chip-based source of entangled photons ...

Recommended for you

Physicists solve quantum tunneling mystery

19 hours ago

An international team of scientists studying ultrafast physics have solved a mystery of quantum mechanics, and found that quantum tunneling is an instantaneous process.

How spacetime is built by quantum entanglement

19 hours ago

A collaboration of physicists and a mathematician has made a significant step toward unifying general relativity and quantum mechanics by explaining how spacetime emerges from quantum entanglement in a more ...

Experiment confirms quantum theory weirdness

20 hours ago

The bizarre nature of reality as laid out by quantum theory has survived another test, with scientists performing a famous experiment and proving that reality does not exist until it is measured.

Quantum computer emulated by a classical system

20 hours ago

(Phys.org)—Quantum computers are inherently different from their classical counterparts because they involve quantum phenomena, such as superposition and entanglement, which do not exist in classical digital ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.